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Effects of corn particle size and diet form on growth performance of 6-22 kg nursery pigs
A total of 192 pigs (PIC 1050, initially 6.7 kg and 31 d of age) were used in a 35-d study. Pigs were allotted to 1 of 4 dietary treatments (6 pigs/pen and 8 pens/treatment). The nutritionally similar 4 diets were arranged in a 2 × 2 factorial consisting of: (1) corn ground to ~387 µm in meal form; (2) corn ground to ~ 703 µm in meal form; (3) treatment 1 in pellet form; (4) treatment 2 in pellet form. Data were analyzed using the GLIMMIX procedure of SAS. Overall (d 0 to 35), there were no effects of corn particle size (P > 0.24). However, pigs fed mash diets had improved overall ADG compared to those fed pelleted diets (P = 0.01; 0.43 vs. 0.39 kg/d), which was primarily driven by greater ADFI. In fact, pigs fed mash diets had greater ADFI during all periods (P < 0.02). Still, feed efficiency was improved by pigs consuming mash diets compared to those consuming pelleted diets from d 0 to 14 (P < 0.0001; 0.57 vs. 0.68), but there were no differences from d 14 to 35 or overall. There was no corn particle size × feed form interaction on ADG or ADFI (P > 0.17), but pigs fed pelleted diets from 700 micron corn had improved overall feed efficiency compared to pigs fed any of the other three treatments (P < 0.05), including those fed pelleted diets from 400 micron corn. As expected, the diet manufactured in mash form from the 700 micron corn resulted in the poorest feed efficiency numerically. This research suggests that feed efficiency is slightly improved by feeding 400 vs. 700 micron corn in mash diets, but pelleting does not further improve feed efficiency when corn is ground to a fine particle size. Interestingly, pelleting diets manufactured from larger particle size corn improved feed efficiency more than those made with smaller particle size in this experiment. More research is needed to confirm and explain this finding.
Keywords: nursery pig, particle size, pelleting